U.S. patent application number 14/173154 was filed with the patent office on 2014-08-14 for communication module.
This patent application is currently assigned to Control Techniques Limited. The applicant listed for this patent is Control Techniques Limited. Invention is credited to Bryce Trevor BEESTON, James Robert Douglas KIRKWOOD, Luke Duane OREHAWA, Richard Mark WAIN.
Application Number | 20140226680 14/173154 |
Document ID | / |
Family ID | 47998844 |
Filed Date | 2014-08-14 |
United States Patent
Application |
20140226680 |
Kind Code |
A1 |
WAIN; Richard Mark ; et
al. |
August 14, 2014 |
COMMUNICATION MODULE
Abstract
A control module for use within a control network, the control
module comprising: interface circuitry for enabling communication
with an external device; communication means configured to
communicate with the external device over the control network by
communication with the interface circuitry; coupling means
configured to mechanically couple the control module to an adjacent
control module and provide a data connection between the
communication means and the adjacent module; and an electrical
isolation in the data connection between the communication means
and the coupling means.
Inventors: |
WAIN; Richard Mark;
(Newtown, GB) ; BEESTON; Bryce Trevor; (Newtown,
GB) ; OREHAWA; Luke Duane; (Newtown, GB) ;
KIRKWOOD; James Robert Douglas; (Church Stretton,
GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Control Techniques Limited |
Newton |
|
GB |
|
|
Assignee: |
Control Techniques Limited
Newton
GB
|
Family ID: |
47998844 |
Appl. No.: |
14/173154 |
Filed: |
February 5, 2014 |
Current U.S.
Class: |
370/466 |
Current CPC
Class: |
H04L 12/413 20130101;
H04L 12/4625 20130101 |
Class at
Publication: |
370/466 |
International
Class: |
H04L 29/06 20060101
H04L029/06; H04L 29/08 20060101 H04L029/08 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 8, 2013 |
GB |
1302278.5 |
Claims
1. A control module for use within a control network, the control
module comprising: interface circuitry for enabling communication
with an external device; communication means configured to
communicate with the external device over the control network by
communication with the interface circuitry; coupling means
configured to mechanically couple the control module to an adjacent
control module and provide a data connection between the
communication means and the adjacent module; and an electrical
isolation in the data connection between the communication means
and the coupling means.
2. A control module according to claim 1, wherein the interface
circuitry is electrically connected to the communication means.
3. A control module according to claim 1, wherein the interface
circuitry and the communication means are at the same voltage
potential.
4. A control module according to claim 1, wherein the interface
circuitry and the communication means are not isolated from one
another.
5. A control module according to claim 1, wherein the interface
circuitry is in communicative connection with the control network
through the communication means.
6. A control module according to claim 1, wherein the coupling
means comprises one part of a cooperating mechanism.
7. A control module according to claim 1, wherein the control
module comprises two or more coupling means connected to the
communication means; and optionally each coupling means is
connected to the communication means through separate isolation;
and optionally each coupling means comprises part of a cooperative
coupling mechanism.
8. A control module according to claim 1, wherein the coupling
means comprises electrical contacts in order to make the data
connection; and optionally the electrical contacts are configured
to form an electrical contact with an adjacent control module when
the control modules are coupled.
9. A control module according to claim 1, wherein the communication
means is configured to act as a network node; and optionally the
communication means is configured to use a single communication
protocol; and optionally the communication means is configured to
communicate using a communication protocol which specifies
electrical isolation; and optionally the communication means is
configured to communicate using Ethernet.
10. A control module according to claim 1, wherein the isolation
conforms to a communication protocol which specifies electrical
isolation; and optionally the isolation comprises a
transformer.
11. A control module according to claim 1, wherein the interface
circuitry comprises an earth connection.
12. A control assembly comprising two or more control modules
according to claim 1 which are mechanically coupled to one another,
for example through respective coupling means.
13. A control assembly according to claim 12, wherein each control
module of the control assembly is configured to form a node of the
control network; and optionally the communication means of each
control module is configured to communicate using the same
communication protocol.
14. A control assembly according to claim 12, wherein the control
assembly further comprises an interface unit configured to provide
an electrical interface between the control assembly and the
remainder of the control network; and optionally the interface unit
comprises passive circuitry; and optionally the passive circuitry
is configured to perform electrical signal conditioning; and
optionally the interface unit does not comprise active
circuitry.
15. A control assembly according to claim 14, wherein the interface
unit comprises a first connector configured to connect to an
external communication connection of at least one of the control
modules; and optionally the interface unit comprises a second
connector configured to connect to the remainder of the control
network; and optionally the second connector is configured to
connect to a cabled plug.
16. A control assembly according to claim 14, comprising two or
more interface units; and optionally an interface unit is
integrated into a control module.
17. A control assembly according to claim 12, wherein the control
network uses a single communication protocol.
18. A control network comprising one or more control modules
according to claim 1.
19. A control network comprising one or more control assemblies
according to claim 12.
20. A control module according to claim 1 wherein the data
connection is provided between the communication means of the
control module and a corresponding communication means of the
adjacent control module.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit and priority of Great
Britain Patent Application No. 1302278.5 filed Feb. 8, 2013. The
entire disclosure of the above referenced application is
incorporated herein by reference.
FIELD
[0002] This invention relates, but is not limited, to the
implementation of communication modules, communication assemblies
and communication networks, such as control modules, control
assemblies and control networks within an industrial control
environment.
BACKGROUND
[0003] Communication applications, such as industrial control
applications, can be harsh environments for the transmission of
communication signals within a communication network. This is in
part due to the amount of electromagnetic noise within the
environment. As such, communication protocols and transmission
media through which the communication signals are transmitted often
have to be robust so that they can withstand the potentially
corrupting effects of electromagnetic interference. Communications
which are robust to such noise typically require high transmission
power and/or resilient signalling techniques. In addition, in some
environments the distance covered by communication signals may be
large, which provides further constraints upon the implementation
of a communication network within an industrial control
environment.
[0004] Industrial control environments typically implement
communication networks, such as control networks, comprising a
number of control modules which may act as nodes for the network.
In some control networks, some nodes are displaced from others,
whilst other nodes are grouped together in close proximity. Where
some of the modules or nodes are located in close proximity, such
as to take measurements or transmit control signals to a particular
device or for other actions to take place, the relevant modules may
also be mechanically coupled to one another. In an attempt to
reduce the cost of implementing a control network, it is common to
separate communications into sections which use different
protocols. A first protocol may be used for communication over a
long distance in an often noisy environment and a second,
different, communication protocol used for communication between
modules which are grouped together.
[0005] The second protocol may be a simpler or less robust protocol
than the first protocol because it is operating in a relatively
benign environment often between mechanically coupled modules. The
second protocol may differ in that the packet structures and/or
physical layer properties are not the same as the first protocol.
As such, the displaced nodes within the control network may
communicate using a first protocol and a group of nodes within the
control network may separately communicate with one another using a
second protocol. Such arrangements require protocol conversion
circuitry to convert between the first protocol and the second
protocol. The protocol conversion circuitry, however, is typically
active circuitry which requires external electrical power and
signal processing which increases the power requirements, cost and
complexity of the control network implementation and may also add
processing delays to the communication. This is particularly
disadvantageous for industrial control environments which may
require fast acting real time or deterministic communication.
[0006] What is needed is an implementation of communication within
a control network in which the cost and complexity is reduced
without negatively impacting upon the effectiveness of the network
communication.
SUMMARY
[0007] According to disclosed embodiments there is provided a
control module for use within a control network, the control module
comprising: interface circuitry for enabling communication with an
external device; communication means configured to communicate with
the external device over the control network by communication with
the interface circuitry; coupling means configured to mechanically
couple the control module to an adjacent control module and provide
a data connection between the communication means and the adjacent
module; and an electrical isolation in the data connection between
the communication means and the coupling means.
[0008] By providing a control module which comprises coupling means
configured to mechanically couple the control module to an adjacent
control module in addition to electrical isolation in the data
connection between a communication means and the coupling means of
the communication module, it is possible to implement
communication, such as control communication, between modules using
only a single communication protocol in a cost effective manner
which does not negatively impact upon the operation of each
communication module. By providing isolation between coupling means
and the communication means of a particular communication module,
the amount of noise current which passes through the communication
means is reduced. The isolation of the communication module not
only isolates the communication means from other elements of the
communication network but also prevents noise currents induced in
the interface circuitry of the communication module from negatively
impacting the operation of the communication means.
[0009] This is particularly advantageous in communication networks
where only a single communication protocol is deployed since the
isolation provided between the coupling means and the communication
means may be stipulated in some way by the communication protocol.
Moreover, these features enable the deployment of a communication
network, such as a control network, using a single, unified
communication protocol without requiring the deployment of
additional and significant isolation within the communication
module.
[0010] By providing this capability, it is also not necessary to
perform protocol conversion within a communication assembly such as
a control assembly, since all of the elements use the same
communication protocol as the remainder of the communication
network. As such, it is possible to implement the integration of
mechanically coupled modules into a communication network without
the need for a second communication protocol and a protocol
converter. This is because the implementation of a robust
communication protocol within mechanically coupled communication
modules is simplified by providing a connection between the
interface circuitry and the communication means without negatively
impacting upon the operability of the individual modules.
[0011] It is to be understood that other aspects of the present
disclosure will become readily apparent to those skilled in the art
from the following detailed description, wherein various
embodiments of the disclosure are shown and described by way of
illustration. As will be realized, the disclosure is capable for
other and different embodiments and its several details are capable
of modification in various other respects, all without departing
from the spirit and scope of the present disclosure. Accordingly
the drawings and detailed description are to be regarded as
illustrative in nature and not as restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Embodiments will now be described by way of example with
reference to the accompanying drawings in which:
[0013] FIG. 1 is a view of coupled control modules;
[0014] FIG. 2 is a view of a control module according to the
present disclosure;
[0015] FIG. 3 is a view illustrating noise current flow through
mechanically coupled control modules;
[0016] FIG. 4 is a further view of a control assembly;
[0017] FIG. 5 is a further view of the control assembly of FIG. 4;
and
[0018] FIG. 6 is a further view of the control assembly of FIG.
5.
DETAILED DESCRIPTION
[0019] FIG. 1 illustrates an arrangement of control modules in a
control network, such as an industrial control network. A number of
control modules 10a, 10b, 10c are shown, in which electrical
connectivity is provided between the modules 10a, 10b, 10c. Each
control module 10a, 10b, 10c comprises a communication means 11a,
11b, 11c which is formed of electrical circuitry necessary to
enable communication between each of the communication means 11a,
11b, 11c. Each control module 10a, 10b, 10c also comprises an
isolation barrier 12a, 12b, 12c which comprises electrical
isolation configured to inhibit the passing of electrical noise
through the control modules 10a, 10b, 10c. Each control module 10a,
10b, 10c also comprises interface circuitry 13a, 13b, 13c, which
comprises electrical circuitry configured to interact with external
devices. The interaction between the interface circuitry 13a, 13b,
13c and external devices exposes the control module 10a, 10b, 10c
to noise and thus noise currents may be induced within each control
module 10a, 10b, 10c. The isolation barriers 12a, 12b, 12c are
configured to reduce the noise currents flowing through and
possibly corrupting the communication means 11a, 11b, 11c and the
interface circuitry 13a, 13b, 13c.
[0020] As also illustrated in FIG. 1, previously the control
modules 10a, 10b, 10c required protocol conversion units 14a, 14b
which are attached at either end of the coupled control modules
10a, 10b, 10c. The protocol conversion units 14 convert the
protocol used by the communication means 11a, 11b, 11c to a
different communication protocol and/or different physical layer
implementation which is typically more noise robust in order to
enable communication beyond the mechanically coupled control
modules 10a, 10b, 10c. In order to convert protocols, the protocol
conversion units 14 comprised active circuits 14a, 14b which
required electrical power and typically used a processor in order
to perform the protocol conversion.
[0021] FIG. 2 illustrates a communication module 20 of the present
disclosure. The communication module 20 is a control module which
comprises a communication means 21 which is configured to act as a
network node to enable communication with other control modules
within a communication network, such as a control network 100,
using a particular communication protocol. For example, the
communication means 21 may be configured to communicate over
Ethernet at a number of different data rates, such as 10 BASE-T,
100 BASE-TX, 1000 BASE-T, or 10 GBASE-T. Other protocols that can
be used in a control environment can be used. The communication
means 21 comprises electrical circuitry, for example signal
transceivers, signal conditioning circuitry and/or a processor. The
communication means 21 is configured to enable communication
handshaking or to perform collision detection and/or any other
functions required in order to communicate through the control
network 100. The communication means 21 may also comprise other
elements which enable the control module 20 to act as a node or
element on the control network 100. In some embodiments, the
communication means 21 does not comprise electrical isolation.
[0022] As illustrated in FIG. 2, the control module 20 comprises an
external network connection. In some embodiments, the external
network connection comprises one or more coupling means 25
configured to provide mechanical coupling between the control
module 20 and other adjacent control modules. The coupling means 25
may be formed of one half of a cooperating mechanism which enables
the control module 20 to mechanically connect to an adjacent
module. In some embodiments, the mechanical coupling may be such
that the control modules are coupled together substantially along a
common axis, although other configurations and arrangements of the
control modules can be used.
[0023] The coupling means 25 may comprise a simple releasably
engageable mechanism, such as a simple locking mechanism in order
to ensure a reliable mechanical coupling between adjacent control
modules. For example, the cooperating coupling means may include a
tab in order to couple adjacent control modules. The coupling means
25 may also comprise one or more electrical contacts. The
electrical contacts of adjacent control modules are directly
connected when adjacent control modules are mechanically coupled.
In this way, the electrical connection between the control modules
is made by the coupling and maintained throughout mechanical
coupling. In some embodiments, the coupling means may comprise a
slidable mechanism in order to mechanically couple adjacent control
modules together. In some embodiments, the slidable mechanism may
comprise electrical contacts which are configured to engage
cooperating electrical contacts of an adjacent control module as
the modules slidably engage. In some embodiments, the slidable
mechanism may comprise a protrusion and a channel which are
configured to cooperate. In some embodiments, each control module
comprise both a protrusion and a channel. In some embodiments, the
protrusion and the channel of each control module may extend along
a length of the control module. In other embodiments, the
protrusion and the channel may extend along a portion of a length
of the control module.
[0024] In some embodiments, the control module 20 may comprise more
than one coupling means 25. In some embodiments, the control module
20 may comprise a first coupling means 25a and a second coupling
means 25b. The first and second coupling means 25a, 25b may differ
and be configured to cooperate with each other. As such, one of the
first 25a or second 25b coupling means may cooperate with a
corresponding coupling means of an adjacent control module. For
example, the first coupling means 25a of the control module may be
configured to cooperate with and mechanically couple to a
complementary second coupling means 25b of an adjacent control
module. Similarly, the second coupling means 25b of the control
module may be configured to cooperate with and mechanically couple
to a first coupling means of an adjacent control module. In this
manner, it is possible to mechanically couple a plurality of
control modules together. In some embodiments, the coupling means
need not be located opposite one another on the control module and
may be placed elsewhere on the control module.
[0025] The control module 20 of FIG. 2 also comprises electrical
isolation 22, which is connected between the coupling means 25 and
the communication means 21. In some embodiments, the electrical
isolation 22 comprises a transformer. In some embodiments, the
communication protocol used by the communication means 21 specifies
the requirements for electrical isolation 22. In the embodiment
where the protocol defines the degree or type of isolation, the
electrical isolation may be configured to conform to that
specification. For example, the communication means 21 may be
configured to communicate using Ethernet. In that example, the
isolation 22 may be configured to conform to the Ethernet
standard.
[0026] In some embodiments, where the control module 20 comprises
two or more coupling means 25a, 25b, the control module 20 may
comprise electrical isolation 22 between each coupling means 25a,
25b and the communication means 21. In this way, the communication
lines that pass between communication means of adjacent control
modules are isolated from each other.
[0027] Control module 20 further comprises interface circuitry 23
configured to electrically connect to the communication means 21
and provide an external electrical connection for the control
module 20. The interface circuitry 23 of the control module 20 is
configured to interact with external devices within the industrial
control environment as part of the control functionality provided
by the control network 100. The external devices may not be, of
themselves, connected to or in communication with the control
network 100. In some embodiments, the interface circuitry 23 may be
configured to communicate with, take measurements from or otherwise
control an external device or module through the external
electrical connection it provides. As such, the interface circuitry
23 may be exposed to external noise, typically in the form of noise
currents induced into the interface circuitry 23.
[0028] The communication between the external device and the
control network may include the supply of electrical power or the
provision of at least one control signal to control the operation
of the external device through the interface circuitry. The
external device may be any device which is used in an industrial
control environment. The external device may by any type of
actuator, motor, or drive. For example, the external device may be
an AC motor, a DC motor, a servo. Such external devices commonly
induce noise currents. The external device may provide feedback to
the control device 20 through the interface circuitry 23.
[0029] The interface circuitry 23 may be configured to communicate
with the communication means 21 so that data may be passed between
them. The communication link between the interface circuitry 23 and
the communication means 21 enables the passing of information
between the interface circuitry 23 and the rest of the network. As
such, data collected from the interface circuitry 23 is available
to the rest of the network through the communication means 21. In
addition, messages, such as control messages, sent through the
control network 100 may be passed to the interface circuitry 23 in
order for the interface circuitry 23 to operate as intended by the
network.
[0030] The connection between the communication means 21 and the
interface circuitry 23 may be a direct connection. For example, the
communication means 21 and the interface circuitry 23 may connect
such that no elements are placed between them. In some embodiments,
the communication means 21 and the interface circuitry 23 may be
connected such that they share the same voltage potential. In some
embodiments, the interface circuitry 23 and the communication means
21 may not be electrically isolated from one another.
[0031] In some embodiments, the interface circuitry 23 and the
communication means 21 may each comprise a controller, such as a
microprocessor, Programmable Logic Device (PLD), Programmable Logic
Controller (PLC) or Field-Programmable Gate Array (FPGA) configured
to control the operation of the interface circuitry 23 and the
communication means 21. In some embodiments, one of the interface
circuitry 23 and the communication means 21 may comprise a
controller that is configured to control the operation of the
other. In some embodiments, the control module 20 may comprise a
controller, separate from the interface circuitry 23 and the
communication means 21, and which is configured to control both the
communication means 21 and the interface circuitry 23. The
particular implementation of the controller to operate the
interface circuitry 23 and the communication means 21 is well
within the routine design choices of the skilled person.
[0032] By connecting the interface circuitry 23 to the
communication means 21, the interface circuitry 23 is exposed to a
potentially noisy environment. As discussed above, the noise
generated from the external sources may present itself as noise
currents within the interface circuitry 23 located within the
control module 20. Prior network modules have overcome this problem
by utilising an isolation barrier, commonly in the form of
opto-isolators and/or DC-DC converters placed between interface
circuitry and communication means in order to ensure that external
noise does not interfere with the communication means.
[0033] In the arrangement of FIG. 2, isolation 22 is provided
between the communication means 21 and each coupling means 25a,
25b. By providing the isolation 22 between the communication means
21 and the coupling means 25a, 25b, the isolation 22 is capable of
reducing the flow of noise current through the communication means
21 or the communication lines which are used to connect the
communication signals between nodes of the control network 100.
[0034] It is known from the electrical theory relating to
Kirchhoff's current laws that the total electrical current flowing
into an electrical node is equal to the total electrical current
flowing out of that node. Therefore, by providing isolation 22
between the coupling means 25 and the communication means 21, the
noise current flowing out of the control module 20 through the
coupling means 25 is reduced. As such, the amount of current that
flows through the communication means 21, is also reduced.
Therefore, isolation between the communication means 21 and the
interface circuitry 23 is not required in order to reduce the noise
current passing through the communication means 21.
[0035] The reduced current flow due to the isolation 22 is
particularly advantageous in arrangements where the communication
protocol used by the communication means 21 to enable communication
over the control network 100 utilises, recommends, specifies or
demands some form of isolation between nodes of the network. For
example, this occurs where the protocol specifies that the
communication means of a particular node is electrically isolated
from the other nodes of the network. One such example of a
communication protocol which specifies isolation in this way is
Ethernet (IEEE 802.3) which is the basis of the exemplary
embodiments described herein.
[0036] Communication protocols, such as Ethernet, may be used over
long distances and thus can exhibit problems relating to the
physical separation of nodes. For example, differences in potential
at each node may cause issues such as ground offsets between the
nodes. As such, in order to comply with some communication
protocols, it is desired or necessary to implement electrical
isolation between nodes. This isolation may also provide short
circuit protection from other nodes.
[0037] Therefore, the isolation 22 performs two separate isolating
functions using the same element. The first function provided by
the isolation 22 being placed between the communication means 21
and the coupling means 25 is to aid the communication of data
within /the control network 100 by isolating each network node, or
control module, from the other network nodes in the network whilst
also providing short circuit protection for each network node. The
second function provided by the isolation 22 placed between the
coupling means 25 and the communication means 21 is the isolation
or reduction of the external noise currents which are induced
through the interface circuitry 23 and interact with the
communication means 21.
[0038] FIG. 3 illustrates the noise current flow through an
exemplary control module 20. Electrical current is known to flow to
an earth or GND connection, and the amount of current flowing
through different electrical paths to earth will depend upon the
electrical impedance of that path. In the exemplary arrangement
illustrated in FIG. 3, in the circumstance where the isolation is
not provided, the noise current is able to flow through the
communication means 21 and may be detected on the communication
lines such that it flows to an adjacent module 30 in order to flow
to earth. This is illustrated in FIG. 3 by the solid black line.
The applicants have recognised that, by reducing or inhibiting the
amount of noise current that is able to flow through the isolation
22, the amount of noise current that flows through the
communication means 21 is also reduced or inhibited, since the
noise current will find another route to earth. This is indicated
in FIG. 3 by the dashed line. Any noise current that would that
would have passed through the communication lines to the adjacent
control module 30, would also have had to pass through the
communication means 21. Since the noise current path through the
communication lines to earth is removed by the isolation, the
current that would have passed through the communication lines must
flow to earth through another path. As such, less noise current
passes through the communication means 21 than would occur if no
isolation 22 were in place.
[0039] In some embodiments, the communication protocol used by the
communication means 21 does not stipulate a particular degree or
type of isolation. In some embodiments, the isolation 22 may be
implemented simply as best practice for communication.
[0040] By providing isolation 22, the noise currents entering the
control module 20 through the interface circuitry do not interfere
with or upset the communication means 21 to the same degree as if
the isolation 22 were not present since a reduced amount of noise
current will flow through the communication means 21. Moreover, the
isolation 22 reduces any noise currents from flowing onto the
communication lines or to an adjacent control module 30.
[0041] FIG. 4 illustrates an embodiment of the present disclosure
in which a control assembly comprises control modules 20a, 20b and
20c that are mechanically coupled to one another through respective
coupling means 25, in the manner previously described. As also
previously described, the mechanical coupling of the modules 20a,
20b, 20c also provides electrical connectivity between the modules
20a, 20b, 20c through the use of electrical contacts which are made
when the modules are mechanically coupled. This electrical
connectivity enables electrical communication through each module
20a, 20b, 20c to form an arrangement of nodes within a network. The
communication lines between the control modules 20a, 20b, 20c are
therefore connected so that the control modules 20a, 20b, 20c are
in communicative connection with each other.
[0042] Each module 20a, 20b, 20c comprises communication means 21a,
21b, 21c which enables communication between the control modules
20a, 20b, 20c using a standard and unified communication protocol
across all of the control modules 20a, 20b, 20c which are
mechanically coupled to one another. Each control module 20a, 20b,
20c is configured to act as a node in the control network 100 since
the communication means 21 of each control module 20a, 20b, 20c may
be configured to operate as a node on the control network 100. Each
control module 20a, 20b, 20c which acts as a node of the control
network 100, is electrically isolated from adjacent nodes by the
isolation provided between each respective communication means 21a,
21b, 21c.
[0043] In some embodiments, where the control modules are arranged
as illustrated in FIG. 4, it may be necessary only to include a
single element of isolation 22 for each control module 20a, 20b,
20c. For example, by providing isolation only to the first coupling
means 25a for each control module 20a, 20b, 20c, it is possible to
isolate each control module from the other control modules by
virtue of the isolation in the adjacent control module, e.g. by
utilising the isolation of the second coupling means 25b of the
adjacent control module 20a, 20b, 20c.
[0044] It will be appreciated that, in some embodiments of the
control assembly 50, the control modules 20a, 20b, 20c may be
electrically powered separately and individually. In some
embodiments, the electrical power and earth connections may be
passed between modules. In some embodiments, the electrical power
and earth connections may be passed through the coupling means 25.
Careful routing of the power and earth connection may also reduce
the amount of noise currents that are introduced in to the
communication means 21.
[0045] As also shown in FIG. 4, each control module 20a, 20b, 20c
comprises interface circuitry 23a, 23b, 23c configured to connect
to external devices 27a, 27b, 27c. In some embodiments, the
interface circuitry 23a, 23b, 23c may be configured to communicate
different aspects or elements of the same device. In some
embodiments, the interface circuitry 23a, 23b and 23c may comprise
identical circuitry or may comprise different circuitry depending
upon the function required.
[0046] FIG. 5 illustrates an exemplary arrangement of the present
disclosure in which coupled modules 20a, 20b, 20c are in
communicative connection with interface units 29. The interface
units 29 are configured to provide connectivity between the control
modules 20a, 20b, 20c which are mechanically coupled together and
the remainder of the control network 100. In the arrangement shown
herein, the control network 100 may utilise a single communication
protocol across the entire control network 100. As such, the
interface units 29 are not required to perform any protocol
conversion, or to change the signal levels of the communication
signals. Moreover, the interface units 29 are not required to
modify the data format of the communication signals. By providing a
single communication protocol for the entire control network 100
the interface units 29 need only change the routing of the
communication signal from one connector type to another.
[0047] For example, in some embodiments of the present disclosure
the physical connection between the control modules 20a, 20b, 20c
modules may be made using electrical contacts. In this manner, it
is not necessary to utilise separate cabling in order to ensure
electrical contact between coupled control modules 20a, 20b, 20c.
The electrical contact between coupled control modules 20a, 20b,
20c is made when the control modules 20a, 20b, 20c are mechanically
coupled to each other. However, in order for the coupled control
modules 20a, 20b, 20c to be electrically connected with remote
control modules or other nodes of the network, it is typically
required to use an additional connection, such as to separate
cabling. As such, the interface unit 29 must provide an interface
between a connector which is configured to connect to the remainder
of the network, for example via a cable and a directly engaged
connector, such as through coupling means 25.
[0048] Therefore, the interface unit 29 provides a physical
interface which comprises at least two physical connections. One of
the physical connections is configured to cooperate with the
coupling means 25 of a particular control module 20. The interface
unit 29 therefore is configured to mechanically couple to a control
module in order to provide an electrical connection between the
interface unit 29 and the control module 20. In this way, the
communication signals from the coupled control modules 20a, 20b,
20c are passed to the interface unit 29. In some embodiments, the
interface unit 29 comprises a cooperative half of a coupling means
25 in order to cooperatively couple with a control module 20. In
some embodiments, the interface unit 29 may have either a first
coupling means 25a or a second coupling means 25b. In some
embodiments, the interface unit 29 may comprise a first 25a and a
second 25b coupling means in order to enable connection in a
variety of different ways.
[0049] The interface unit 29 also has another physical connection
comprising a mechanical connection which is configured to provide
an external electrical connection to the remainder of the control
network 100 via a cable or external interface. In some embodiments,
the second mechanical connection of the interface unit 29 is
configured as a socket in order to mate with an external plug.
Conversely, the interface unit 29 may be configured as a plug in
order to connect with an external socket arrangement. In some
embodiments, the second physical connection may be configured to
engage with an industry standard connector, such as an RJ45 (8P8C)
connector.
[0050] By doing so, the electrical communication signals are simply
transferred between the physical connections of the interface unit.
Specifically, the communication signals are transferred between the
contacts of the external cabling to that of the electrical
connections provided by the coupling means 25. For example, the
external electrical cabling may require a particular arrangement in
order to operate within the noisy control environment, such as
electrical shielding or a twisted pair arrangement. Conversely,
this may not be necessary for transmission between the coupled
modules 20a, 20b, 20c and thus a straight-through connection may be
possible.
[0051] The interface unit 29 may also comprise internal circuitry
29a, 29b. Since the signals that are passed through the interface
unit 29 are of the same protocol and are also the same,
electrically, it is not necessary to perform any protocol
conversion. However, in some embodiments, it may be beneficial to
include passive circuitry 29a, 29b in order to perform signal
conditioning on the electrical signals passing through the
interface unit 29. The passive circuitry may include electrical
components that do not require an external power source, such as
resistors, capacitors and inductors, which are configured to
improve the signal quality, for example by providing filtering.
[0052] Since the interface unit 29 utilises passive components and
does not require active electrical components. The quality of the
communication signals is improved at low cost and complexity.
Further advantageously, it is not necessary to implement complex or
power intensive circuitry in order to perform protocol
conversion.
[0053] As shown in FIG. 5, the coupling means 25 at each end of the
coupled control modules 20a, 20b, 20c may be connected to a
respective interface unit 29. As such, it is possible to use
multiple external connections to the control network 100. One
advantage of this arrangement is that it is possible to enable
redundancy within the connectivity of the control network 100. For
example, if one of the passive circuits 29a were to fail, it would
still be possible for communication between the coupled control
modules 20a, 20b, 20c and the remainder of the control network 100
to occur through the other passive circuit 29b.
[0054] FIG. 6 illustrates a control assembly 50 wherein an
interface unit 29 is physically integrated within a control module
20d. In this arrangement, the interface unit 29 is used to provide
the external physical connection to the remainder of the control
network 100, as described above with respect to FIG. 5. However,
since the interface unit 29 is integrated within a control module
20d, it is not necessary to provide a separate unit and an
additional mechanical coupling. Moreover, the passive circuitry 29a
may directly connect to the isolation 22 of that particular control
module 20d.
[0055] By providing a control module 20d with an integrated
interface unit 29 the cost and complexity of providing connectivity
to the remainder of the control network 100 is reduced, since it is
not necessary to manufacture a separate unit for interfacing.
[0056] Moreover, as seen from FIG. 6, a modular control assembly 50
is provided since it is possible to use a combination of different
elements in order to form the control assembly 50. For example, in
FIG. 6 the modular control assembly 50 is formed of a number of
different elements including two control modules 20b, 20c, a
control module comprising an integrated interface unit 29 having
passive circuitry 29a and a separate interface unit 29 that
comprises passive circuitry 29b.
[0057] It will be appreciated that a number of different
arrangements of these modular elements may be provided, including
any number of control modules which are mechanically coupled to one
another. To connect the control assembly 50 to the remainder of the
control network 100, the control assembly 50 may comprise at least
one interface unit 29. However, it will be appreciated that it is
not necessary for the control assembly 50 to comprise a separate
interface unit 29. The control assembly 50 may simply comprise a
control module 20d with an integrated interface unit in order to
communicate with the remainder of the control network 100.
[0058] The constituent hardware elements, operating systems and
programming languages of the components of the present disclosure
may be conventional in nature, and it is presumed that those
skilled in the art are adequately familiar with them. Of course,
the processing functions may be implemented in a distributed
fashion on a number of similar platforms, to distribute the
processing load.
[0059] Aspects of the methods and apparatuses described herein can
be executed in a particular module. Those skilled in the art will
appreciate that while the foregoing has described a particular
mode, and where appropriate other modes, of performing the
invention, the invention should not be limited to specific
apparatus configurations or method steps disclosed. It is
understood that various modifications may be made and that the
subject matter disclosed may be implemented in various forms and
examples, and that the teachings may be applied in numerous
applications, only some of which have been described herein. It is
intended by the following claims to claim any and all applications,
modifications and variations that fall within the true scope of the
present teachings. Those skilled in the art will recognize that the
invention has a broad range of applications, and that the
embodiments may take a wide range of modifications without
departing from the inventive concept as defined in the appended
claims.
[0060] A number of embodiments have been described herein. However,
it will be understood by persons skilled in the art that other
variants and modifications may be made without departing from the
scope of the embodiments as defined in the claims appended
hereto.
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